When using AdSense for search, what is the key factor determining ad placement within search results?

When using AdSense for search, the key factor determining ad placement within search results is the ad auction, which considers both the advertiser's bid and the quality of the ad in relation to the user's search query. While a higher bid increases the likelihood of an ad being displayed prominently, Google also prioritizes ads that are highly relevant to the search terms and offer a good user experience. Factors such as ad relevance, landing page quality, and expected click-through rate all contribute to the ad's overall quality score. Ads with a higher quality score are more likely to appear in top positions, even if their bids are slightly lower than other ads. This ensures that users see ads that are both useful and relevant to their search, while also providing advertisers with an incentive to create high-quality campaigns.